1. Field of the Invention
This invention relates to a falling particle televising apparatus in a weather-resisting snowfall testing system in which the condition and particle size distribution of the growing crystals of snow produced artificially in a snow generating chamber and a weather-resisting snowfall testing chamber are observed. The results of the observation are used to vary the various artificial snowfall conditions, such as the speed of an ascending air current, temperature, quantity of cloud and seeding rate in the snow generating chamber, and thereby enable various kinds of snow flakes to fall therein.
2. Description of the Prior Art
A conventional falling particle televising apparatus 55, as shown in FIG. 5, is fixedly mounted in a snow generating chamber (inner cylinder) 51.
Such a conventional weather-resisting snowfall testing system consists of a double casing comprised of an outer casing 50, and the snow generating chamber (inner cylinder) 51. The snow is generated in the snow generating chamber (inner cylinder) 51, and the temperature therein is controlled automatically in an indirect manner by cooling the outer circumferential surface of the same chamber 51. Air is introduced into the snow generating chamber (inner cylinder) 51 from the lower portion thereof in an upward direction and is circulated via a duct by a fan 52, and this upwardly-moving air current can be regulated to flow at an arbitrarily chosen flow rate.
When clouds produced by a humidifier 53 are sent into the snow generating chamber (inner cylinder) 51, they move upwardly due to the upward flow of the air introduced therein. When highly-compressed air is then ejected from a special seeding nozzle (seeding means) 54 into the portion of the interior of the snow generating chamber 51 at which the clouds start moving upwardly, cryohydrate, which constitutes the seeds of snow, is produced due to the adiabatic expansion of the air. The clouds act on these seeds and the seeds grow gradually into snow. Consequently, snow consisting of hexapetalous crystals similar to that of natural snow is obtained.
If various conditions, such as the temperature, quantity of the clouds, quantity of the seeds and speed of the upward flow of the air in the snow generating chamber (inner cylinder) 51 are changed in various ways, artificial snowflakes of various sizes and shapes can be obtained.
In order to selectively generate a certain kind of artificial snow, it is necessary to constantly observe the condition of the cryohydrate and snow crystals produced in the snow generating chamber (inner cylinder) 51. A falling particle televising apparatus 55 as shown in FIG. 4 is used as an observation apparatus for this purpose in the snow generating chamber (inner cylinder) 51.
This televising apparatus 55 is provided with an intake 68 in the upper wall of an apparatus body and a film take-up device 67 under the intake 68, a transparent film 57 being provided on the take-up device 67. The falling particles are deposited on the surface of this transparent film 57 as the film 57 is moved horizontally over a predetermined distance at regular time intervals, and the deposited particles are observed through an objective lens of a television camera 56 provided below the film 57.
Referring again to FIG. 5, reference numeral 58 designates a blower for sending the cooling air from a cooler 59 into the interior of the outer casing 50, numeral 60 designates an air compressor, numeral 61 designates a weather-resisting snowfall testing chamber in which a light source 62, a sample 63 and a turntable 64 are disposed, numeral 65 designates a duct, and numeral 66 designates falling particles.
In order to selectively generate a certain kind of snow, for example snow having thin or large flakes, in the snow generating chamber (inner cylinder), it is necessary that various conditions, such as the temperature, quantity of the clouds, quantity of the seeds and speed of the upward flow of the air in the snow generating chamber (inner cylinder) be changed suitably, and the levels of these conditions are determined and set on the basis of the results, which are obtained from the falling particle television apparatus 55, of the observation of the falling particle generating condition.
However, the conventional televising apparatus is simply fixed in the snow generating chamber (inner cylinder). Therefore, the televising apparatus cannot be controlled from the outside. Hence, the observer has to enter the low-temperature environment to regulate the televising apparatus as necessary. Moreover, only the observation of the falling particles at a limited location in the interior of the cylindrical snow generating chamber (inner cylinder) can be done.
Consequently, only a partial and one-phase observation of the condition of generation of falling particles in the snow generating chamber (inner cylinder) can be done. Accordingly, only very limited information for selectively determining the setting levels of the snow generating conditions can be obtained, so that it is difficult to reliably obtain desired kinds of snowflakes.
Under the circumstances, the development of a falling particle televising apparatus capable of observing the condition of the generation of snow at every portion of the interior of the snow generating chamber (inner cylinder) has been in high demand.
The television camera provided in a conventional falling particle televising apparatus in a snow generating chamber (inner cylinder) is a fixed type television camera. In this television camera, the focal length with respect to the surface of the transparent film is regulated in advance, i.e., the distance between an objective lens, which is threaded to an intermediate ring, and the light-receiving surface of the television camera, is regulated by manually loosening the thread-connected object lens.
Therefore, the focal length cannot be varied during the observation of the falling particles, i.e., the focal length cannot be regulated in accordance with the thickness of the snow crystals.
In such a televising apparatus, falling particles having diameters of ten-odd to several hundred microns are magnified 300-600 times and televised, and the image thus obtained is displayed. Accordingly, the thickness of a crystal appears on the display. In order to observe the spaces above and below this crystal the thickness of which is seen on the display, it is necessary that the focusing be done selectively during the televising of falling particles.
In the prior art falling particle televising apparatus, the focal length is set in advance and cannot be regulated later. Therefore, it is difficult to observe the crystals of falling particles thoroughly and accurately.
In order to solve these problems, the development of a televising apparatus capable of free self-adjustment of its focal length to a selected level has been in demand.
Again, in a conventional televising apparatus, the television camera is fixedly mounted, so that the visual field is also fixed. Consequently, the particles deposited on the surface of the film cannot be moved to the center of the visual field. Namely, only a part of the falling particles collected can be observed in practice.
Furthermore, since the take-up means for the transparent film is moved over a predetermined distance at regular time intervals by a motor and a gear, the feed rate of the film cannot be regulated accurately to any selected level. Therefore, the displaying of a crystal as a whole particle deposited on the central portion of the picture frame for the television cannot be done easily, and the crystals of snow cannot be observed satisfactorily.